In view of a rise in price of gasoline for cars due to the aggravation of oil situation, an attempt to produce inexpensive car fuel by adding mixed alcohols to gasoline have been made in recent years. The reason why mixed alcohols are used as an alcohol component to be added to gasoline is that if methanol alone is added to gasoline, it combines together with water in gasoline to form a water/methanol mixture, resulting in the formation of two layers, i.e., a gasoline layer and a water/methanol mixed layer, in a storage tank.
Various methods of producing such mixed alcohols have been proposed. Japanese Patent Application Laid-Open No. 7727/1981, for example, discloses a process for producing mixed alcohols from synthesis gas by the use of a rhodium-base catalyst. This process, however, is not preferred in that large amounts of by-products such as acetic acid and aldehyde result. In addition, as catalysts for use in the production of mixed alcohols from synthesis gas, a ruthenium-base catalyst (Japanese Patent Application Laid-Open No. 82327/1982), alkali metal-modified ones of a zinc-chromium catalyst and a copper-zinc catalyst (Japanese Patent Application Laid-Open No. 10689/1982), and a copper-cobalt catalyst (Japanese Patent Application Laid-Open No. 85530/1980) are known. Methods utilizing these catalysts, however, should be performed under elevated pressures. This will need expensive equipment and cause many side reactions. Hence they cannot be said to be advantageous for practical use.